With the development of high integration of semiconductor devices, there is a need for an exposure technique for achieving finer patterns, and a new exposure technique is under development. A currently-used light exposure technique uses light from an ArF source. However, due to the long wavelength of such light, it is said that exposure of complicated patterns having a line width of 10 nm or smaller is difficult with this exposure technique.
An exposure technique using charged particle beams is advantageous because charged particle beams have very short wavelength and therefore provide essentially high resolution. However, it is difficult to obtain charged particle beams having sufficient intensity with the exposure technique using charged particle beams. For this reason, a practical processing speed cannot be achieved if only the charged particle beam exposure technique is used to draw fine patterns.
Thus, complementary lithography has been proposed, in which an immersion exposure technique using an ArF light source and a charged particle beam exposure technique are used in a complementary manner. Such complementary lithography is shown, for example, in “Japanese Laid-open Patent Publication No. 61-187234” and “Yasuda et al., Japanese Journal of Applied Physics., Vol. 32, 6012, (1993)”.
In complementary lithography, a simple line-and-space pattern is formed by using double patterning through the immersion exposure using the ArF light source. Next, cutting of the line patterns and formation of via holes are performed through the charged particle beam exposure.
In this lithography technique, the area of a portion exposed to charged particle beams is only about several percent of the overall area of the pattern. For this reason, exposure can be completed with less radiation than in a case where exposure of the pattern is performed using only electron beams for the entire area. This possibly increases throughput.